The Left has traditionally assumed that human nature is so malleable, so perfectible, that it can be shaped in almost any direction. By contrast, a Darwinian science of human nature supports traditionalist conservatives and classical liberals in their realist view of human imperfectibility, and in their commitment to ordered liberty as rooted in natural desires, cultural traditions, and prudential judgments.

Saturday, October 07, 2006

So What's Wrong with Incest?

"Julie and Mark are brother and sister. They are traveling together in France on summer vacation from college. One night they are staying alone in a cabin near the beach. They decide that it would be interesting and fun if they tried making love. At the very least, it would be a new experience for each of them. Julie was already taking birth control pills, but Mark uses a condom too, just to be safe. They both enjoy making love, but they decide never to do it again. They keep that night as a special secret, which makes them feel even closer to each other. What do you think about that? Was it ok for them to make love?"

That's the way Jonathan Haidt began an article on the psychology of moral judgment. He reported that most people immediately condemn what Julie and Mark did as wrong, but they struggle to give reasons for this judgment. I have had the same reaction from students in my classes when I present this story. They react with disgust. But it's hard for them to give reasons to justify their disgust.

Haidt, a professor of psychology at the University of Virginia, argues that this illustrates the primacy of emotion in moral judgment. Against the tendency to explain morality as caused by moral reasoning, he suggests that moral reasoning usually comes after we have already made a moral judgment from our emotional reaction. He also claims that such a view of moral judgment as initially caused by emotional intuition is confirmed by biological psychology.

I agree. In fact, I think the incest taboo is one of the clearest illustrations of how a moral rule can be explained by a Darwinian view of human biological nature. In The Descent of Man, Darwin acknowledged that "of all the differences between man and the lower animals, the moral sense or conscience is by far the most important," and explaining the uniqueness of human moral experience created the "greatest difficulty" for his theory of evolution.

Proponents of the "theory of special creation" would say that that the human moral sense or conscience shows that human beings have been specially created in God's image, so that He has implanted a conscience in them. God's specific commands against incest are found in the Old Testament, in the 18th chapter of Leviticus, which was long adopted in Western legal codes as a set of rules for forbidden marriages.

But Darwin rejected the belief "that the abhorrence of incest is due to our possessing a special God-implanted conscience." He saw the rules for forbidden incestuous marriages as a subject for scientific investigation. During his lifetime, there was an intense debate in England over whether the marriage of first cousins should be prohibited as incest. Darwin had a personal stake in this, since he had married his first cousin (Emma). He proposed that Parliament should authorize a study of cousin marriages to see if their offspring suffered from inherited defects. Although his proposal was rejected, his son George did a study that concluded that the risk for the offspring of cousin marriages was often low.

In his book The Variation of Animals and Plants Under Domestication, Darwin has a chapter "On the Good Effects of Crossing, and On the Evil Effects of Inbreeding." He surveys the experience of animal breeders in discovering the bad effects of inbreeding. And he wonders whether natural selection could have shaped a natural aversion to incest among human beings. "Although there seems to be no strong inherited feeling in mankind against incest, it seems possible that men during primeval times may have been more excited by strange females than by those with whom they habitually lived. . . . If any such feeling formerly existed in man, this would have led to a preference for marriages beyond the nearest kin, and might have been strengthened by the offspring of such marriages surviving in greater numbers."

In Xenophon's Memorabilia (IV.iv.19-23), Socrates identifies the "unwritten laws" legislated by the gods as laws that could not be disobeyed without natural penalties. He speaks of the incest taboo as one of those "unwritten laws," because those committing incest tend to produce defective offspring. Darwin's evolutionary explanation of this would illustrate, then, how Darwinian science might support the traditional idea of "natural law" or "natural right." (I have argued this in a book chapter: "The Incest Taboo as Darwinian Natural Right," in Arthur Wolf and William Durham, eds., Inbreeding, Incest, and the Incest Taboo: The State of Knowledge at the Turn of the Century [Stanford University Press, 2005].)

Edward Westermarck elaborated Darwin's reasoning for the biological evolution of the incest taboo in his book The History of Human Marriage (first published in 1889). Westermarck's theory can be summarized in three propositions. First, inbreeding tends to produce physical and mental deficiencies that lower Darwinian fitness. Second, as a consequence, natural selection has favored an emotional disposition to feel a sexual aversion to those with whom one has been raised in early childhood. Third, this natural aversion to incest creates moral disapproval that is expressed as an incest taboo.

This put Westermarck in conflict with Sigmund Freud's Oedipal theory of human psychology and culture, because Freud insisted that the inclincation to incest was natural to human beings, and that the taboo against incest arose as a purely cultural construction that human beings created to repress their natural desires for incest, this cultural repression of human nature being necessary for civilization. So morality, as Freud understood it, required a conquest of human nature by human culture. By contrast, Westermarck believed that morality was a cultivation of natural human emotions, so that the incest taboo was a cultural expression of a natural human disposition shaped in human evolutionary history.

Over the past century, the evidence for Westermarck against Freud has grown. Arthur Wolf's study of "minor marriages" in China is one line of evidence. A traditional form of Chinese marriage was for parents to give their infant daughter to another family to be raised with the family's infant son, so that when the boy and girl reached maturity, they would be married. Wolf showed that these marriages were generally unsuccessful, because children raised together as siblings developed a sexual aversion to one another.

Another line of evidence came from the experience of the Israeli kibbutzim. In the attempt to create a fully socialist community, the kibbutz would have infant children taken from their families and put in the "children's house," where they would be raised together communally. When they reached sexual maturity, the children were encouraged to find marriage partners among those with whom they had been raised. But the children resisted this, because even though they were not biological relatives, they felt as if they were siblings and thus felt revulsion at the thought of sexual mating with one another.

So it seems that these children in China and in the kibbutzim were manifesting the "Westermarck effect": as a result of an innate disposition shaped by evolutionary history, they developed a sexual aversion to the children with whom they had been raised, even though they were not actually biological siblings.

Another kind of evidence for Westermarck's theory is that it now seems that many primates show incest avoidance. While Freud thought that incest was common among nonhuman animals, we now know that this is not true. For most primate species, males leave their native troop when they reach sexual maturity, which seems to be a mechanism for avoiding excessive inbreeding. For chimpanzees, the females leave at maturity to join another troop. This means that chimp mothers will be in the same troop with their sons. And their sons often do attempt to mount their mothers and sisters, but when the males reach sexual maturity, their mothers and sisters generally push them away. This is what Westermarck's theory would predict. The human incest taboo is humanly unique as a legal and moral norm, but it expresses a natural emotional disposition that can be found in primate evolutionary history.

Freud may have been fooled by his psychoanalytic experience, because in his Vienna, many of his patients had been raised by nurses rather than their parents, and in these conditions, the "Westermarck effect" would not kick in. After all, Oedipus himself was separated from his mother shortly after birth, and so again the sexual aversion to mating with immediate family members would not have been acquired by the Westermarck mechanism.

This Darwinian theory of the incest taboo goes a long way to explaining marriage law. In the United States today, all states prohibit people from marrying their parents, their children, or their siblings. But there is disagreement over cousin marriages. Early in the nineteenth century, all states permitted cousin marriages (as is the case today in Europe). But now cousin marriages are prohibited in 31 states, while being permitted in 19 states. (The debate over cousin marriage is surveyed in Martin Ottenheimer's book Forbidden Relatives [University of Illinois Press, 1996].) There is a good argument for permitting cousin marriage, because we now know that the genetic risk from deleterious recessive genes is often low for cousins, but high for those more closely related. Further, Westermarck's theory would predict that except in cases where cousins are reared together, there will not be a strong moral emotion against cousins mating.

There is great variation in the incest taboos across cultures depending upon the cultural definition of kinship categories. But the variable boundaries of the incest taboos are extensions of an invariant core centered on the nuclear family. The emotional reaction is strongest against incest with one's parents, siblings, and children. The intensity of this emotional reaction fades as one moves away from the nuclear family.

Of course, incest does occur. But the pattern of incestuous behavior follows the predictions of Darwinian theory. Men are more likely to be the perpetrators of incest than are women, because men, unfortunately, are more indiscriminate in their sexual promiscuity. The most common form of incest is actually child abuse--fathers abusing their daughters. And this is more likely to occur if the fathers did not participate in the early rearing of the daughters.

Some people might not feel any moral inhibition against incest because they suffer from a psychopathic poverty of moral emotions. But still, the natural aversion to incest among most human beings is so strong that we formulate moral and legal norms against incest and enforce them as expressions of our natural emotional dispositions.

We can see how reason comes into play here. We might, for example, call on our knowledge of the genetics of inbreeding to rationalize our abhorrence of incest. But this is only a rationalization of a moral abhorrence that causes our moral condemnation of incest as an expression of moral emotion.

39 comments:

The fact that Darwin often resorted to just-so stories rather than science when encountering an apparent contradiction is no excuse for continuing the practice. Wolf's study and the Kibbitzim have both long been debunked, see Marvin Harris' arguments contra, in particular.

The problem with the whole analysis is that marriage (and sex in general) are social actions as much as personal. As such, they are governed by social evolution, which puts vastly different forces in play. Thus, in societies where it was economically advantageous for incest to occur (ie, Roman Egypt) we find a high incidence of incestuous marriages. The reason the incest taboo appears universal, is merely that it is almost always advantageous for societies to use women as a means of exchange. The use of fire is also universal, but requires no genetic explanation.

It is the same forces which will lead a given culture to taboo the eating of a certain food: The ban only works if everyone obeys it. Which begs the question: If there is a natural Darwinian incest avoidance, why the need for a cultural taboo as well?

As for, "men, unfortunately, are more indiscriminate in their sexual promiscuity," I really have nothing to say. Unless they are gay, who are they presumed to be engaging in sex? I enjoy your blog and admire your writing, but aside from the primate studies, you have allowed emotion to run away from science in this post. Cheers.

As far as I know, Marvin Harris never explained Wolf's data indicating that sim-pua girls adopted before age 3 had a much lower rate of fertility that those adopted after age 3. This would be best explained by Wolf's hypothesis that the "Westermarck effect" is strongest when the rearing together occurs before age 3.

The evidence of sibling marriages in ancient Egypt confirms the Westermarck theory. Such marriages were very infrequent. And if we're looking for marriages of full-siblings reared together from an early age, there are no more than a half dozen well-documented cases. Even with these cases, we cannot be sure whether these few marriages were voluntary.

Contra the first comment, as an evolutionary psychologist who has a daughter (age 11) and a son (age 9), I think your ideas here are right on the mark. My wife and I often joke that the constant petty wrangling that goes on between our two kids is just their way of avoiding incest later on. Having grown up with younger sisters myself, I can vouch for the fact that growing up with someone during the "critical period" for incest avoidance does indeed have the effect described by Westermark.

Furthermore, it is not clear at all that Harris's critique actually applies to the kibbutzim example. Harris was a virulent anti-sociobiologist, rejecting any and all attempts to find biological explanations for even the slightest of human behaviors. The obviously Marxist alternative theory (i.e. that females are universally treated as a commodity, and hence any "contamination" of their "market value" via incest was to be avoided) is as ridiculous and counter to empirical evidence as the bankrupt Marxist theory from which it was derived.

As to the suggestion that males stand to lose less from incestuous mating, this is an obvious and simple extrapolation from Trivers's theory of parental investment and sexual selection. Trivers pointed out what Darwin and Bateman (among others) had already suggested: that males have much less to lose by being less "discriminating" about whom they mate with than females. Given the relatively low probability that a homozygous lethal allele combination will result from a full-sibling mating (or a parent-offspring mating) - i.e. one-fourth - males that occasionally mated with their sisters or mothers might actually have higher reproductive success than males that refrained from doing so. A full analysis of the fitness consequences of close-relative mating would therefore involve the calculation of an equilibrium between the negative consequences of inbreeding and the positive fitness consequences of close-relative mating (and comparing males and females using the same criteria). I would not be surprised to discover that certain conditions (e.g. low gene flow/interdemic gene exchange in a chronically isolated population) might actually favor close-relative mating versus incest avoidance.

Note that none of the analysis in the foregoing says anything at all about whether such patterns of mating are "good" or "bad" from a moral standpoint. Evolution, like all natural processes, is quite literally "value free". What we do about its consequences is, as you have repeatedly pointed out, is where morality and values have a legitimate role to play.

Julie and Mark seem to have gotten lost somewhere in the discussion. The college students who evidence revulsion over this story should, rather, simply ape Julie and Mark in their careful contraception,and then proceed with incest themselves. With a little "manly" courage and creativity, our evolved discomfort with incest should be readily overcome.

You're all still living using SELECTIVE evidence, one observation does not make something universal, lastly their is the seedy underbelly of human society that happens behind closed doors. I'm sure there are mother-son, brother-sister, brother-brother, sister-sister, father-daughter, relationships that happen throughout the ages that are simply hidden from the public and scientific eye. After all, if you had the evolutionary trait s where you didn't discriminate based or blood relations, then obviously this is a superior advantage in times of crisis.

As a person who grew up sexually attracted to their sister and his mother, incest is natural, where do you think all human beings came from? Humans had to fuck other humans. You guys are so ignorant it's not funny. Evolution has selected FOR incest and AGAINST incest.

As always the individiaul and human desire to feel superior to others rears it's head, and it is expressed in such posts.

I disagree with the theory of brother/sister incest being avoided because of being reared together. My younger sister and I played together sexually from an early age, and persisted well into adulthood. Niether of us found it abhorant, nor repulsive in any way. Indeed, we were quite excited by the prospect that we both had each other as 'safe' partners during a period in our lives when other options were simply not available as an outlet for our strong sexual drives around the onset of puberty. Theories are nice as far as they go; but imperical evidence does not always back up theory. I've know many other incestuous family groupings that also do not show this 'natural aversion' to incest. I am convinced that all such taboos are cultrually derived, either from observation of genetic defects showing up in livestock, or from religious strictures that are possibly the formalized taboos based on primative observations of like kind. And who is to say that the 'lower' animals don't also have thier form of word of mouth tales and moral codes...? Just because we can't translate thier 'language' doesn't mean they don't have one, or a semblance of it; either verbal or body language or a combination of both. At this stage in our evolution and learning, we have neither the ability to confirm nor the ability to deny such connections. I prefer to remain open minded on the subject.

My sister and I were involved as teenagers off and on for about three years. This is not something that we share with others and we find it almost impossible to discuss with one another. Incestuous relationships do happen, and not always the way they are portrayed on made for TV movies where someone is being abused. I think that incest is almost like an atomic explosion in that it requires a very specific set of circumstances to take place. Exactly why we became involved whereas most siblings do not is something I've never really been able to nail down. We had played doctor together as children and that lowered our aversion to incest I believe. Also we lived in a 1 parent home where our mother was working most of the time, giving us a great deal of time together unsupervised. In that sense it is perhaps not surprising that a sexual relationship developed. Leave two bored teenagers alone together with too much time on their hands and sex is a likely outcome I guess.

While our relationship was consensual, non-abusive and non-exploitive, it also exacted a heavy price. Not 15 minutes after making love for the first time, she and I were both overcome with intense feelings of guilt and shame. No one ever taught us to feel this way, we simply did. These feelings did not go away either, but persisted for years afterwards, creating problems in our relationship that have never been fully resolved. For a long time I considered what we did back then to be the worst thing I'd ever done. Even so that did not stop us. The ability of the human libido to suppress one's moral judgment is truly amazing. What finally ended our sexual relationship was my leaving home to go to college. When she joined me a year later we'd been separated long enough to break the cycle I guess. We've never done anything since then.

When one looks at what happened in a detached light, there is very little logical reason for feelings of guilt or shame. Yet there they are. I've long believed that these feelings are instinctive. As such they are very difficult to put aside and overcome. Even now I still feel some guilt over what we did, even though I intellectually understand it to have been morally neutral.

Um let's see. If we're truly going to look at incest from a biological stance, incest is contradictory to what our biological nature drives us to do. Biologically, humans seek out mates that are genetically different from ourselves in order to disperse a variety of genes into the population. Hence the theory of how females tend to look for mates with immune systems different from their own. Same goes for how according to biological psychology, males want to spread their genes by having sex with several women who are genetically different. It's all about wanting to create genetic diversity, which according to evolution, has allowed for the survival of the fittest.

I disagree with the poster who said evolution has favored incest-- if anything, it's favored against incest. There would be no biological diversity today if incest had continued in the past. Yes, I'm admitting that incest did occur back in the early days of humans, because that was the population's condition. But in addition to our population increase, our morality developed in regards to how we treat each other. Much of that is a cultural phenomenon, but it is also anthropological. It does not make sense to want to screw your own family, when there are genetically different people out there who can stir up the same feelings of desire and lust.

I hate how people try to use the Darwin theory as an attempt to reduce humans to mere scraps of animals whose sole purposes in life is to eat, eliminate, sleep, and screw. Remember people: what separates us from the "animals" is that we have an advanced prefrontal cortex, which we should bother to use from time to time. Incest is genetically averse and morally disgusting.

Alright, it says in The Bible of Jesus Christ that Adam and Eve were the very 1st human beings alive on the earth. Now, if you think about it, they must've had some kids that were incest, and technically if we're all connected to Adam and Eve, we're all connected to each other, but in a much smaller way. In Europe, Kings created marriages between cousins or nephews, or possibly brothers and sisters. Now if you see, incest causes some bad side effects, such as mental insanity, retardation, some symptoms, etc. But as you see today, many people are mentally insane and retarded, so we may possibly be incest, but it's just progressing ever so slowly, and not quicker if a brother and sister make love. Think about it; many criminals are insane (serial killers, rapists, etc.), that may be because we're making love to people that have an incredibly small relationship to you. People on earth are slowly becoming more and more crazy and mad, have any of you noticed that? That's because we may very well be incest and don't even know that fact but just ignore it or don't even know about it! Julie and Mark had not broken any law what so ever, and they used protection as best as they could so, I really don't see the problem.

When people talk about incest in a negative way, they usually talk in terms of how this would affect the offspring. However, when two adult blood relatives have a sexual relationship and use all the necessary precautious against pregnancy (as is used by many other couples) this argument about the offspring loses its force. There is nothing, I believe, in principle so wrong in two relatives having a sexual relationship provided they are not forced or manipulated into it, and they know exactly they are doing. On the contrary, such a relationship may prove to be more loving, enjoyable (and lasting) as it would be based not only on having sex but on friendship and deep mutual understanding (as opposed to many other 'normal' relationships, which all too often lack this).

The fact that God frowns at the act of sexual relationship among people of the same blood, as written in the bible, should be enough basis to stop the act of incest.From the foregoing discussion, it is evident that people always like to give opinnion such that their past deeds would be justified. Dont just think about the fun, also think about the consequence.Even if it is consensual, the memory usually last longer than the fun.

As an atheist myself I am disheartened to see some other atheists saying that incest is not immoral, since it's only a societal taboo or a religious taboo.

They compare opposition to incest as equivalent to anti-homosexuality.

I beg to differ.

I was brought up as christian, but only in a half-assed way, meaning I was allowed to fall asleep during sermons as a child, and as soon as I decided I wanted to nap more comfortably, I didn't have to go to church.

So basically I remained an innocent -- i didn't know even KNOW that homosexuality/incest existed nor that the church taught us to condemn both.

When I first learned of the existence of homosexuality in college I was fascinated but definitely NOT disgusted. There was an innate acceptance in me that two people of same sex should be able to make love if they wanted to, if they were consenting adults.

The effect was quite different when I first heard of incest. A feeling of revulsion engulfed me the same as when I first heard of pedophilia.

Someone here argued for incest by citing Roman Egypt (particularly the royal family I assume) Ironically, in ancient rome, pedophilia was also an accepted practice. So was slavery.

Personally I feel a totally spontaneous revulsion at the idea of having sexual relationship with any of my close kins. Such a reaction was never taught me, as it had not been taught the blogger above who confessed the inexplicable sense of "guilt" over having slept with his sister.

I wondered about this, and had come to the conclusion that it probably have to do with how the human species have evolved, and how we have learned to select partners who are genetically diverse from us, and Westermarck's theory rings true to me.

I believe this natural revulsion to incest exists in most people. There are, of coures, going to be those who are going to differ, since there are always going to be exception to every rule. Unfortunately, these are the people who tend to google "incest" and leave disproportionate amount of pro-incest blogs for articles like these, since most people do not even think that it's a point of debate.

I certainly did not know, until I came across an atheist blog that claimed that incest was not immoral. Unfortunately such people do give atheism a bad name :( (yes, christians, just as you have your nutjobs, so do we, it appears! you can laugh at this one if you want! these people deserve to be laughed at!)

I believe incest is natural, in response to the 5th comment, that yes, where do you think we came from? If Adam and Eve had their children, who do you think they had to mate with? Well, the only ones that were there obviously. Which then leads to us now, so essentially, we are all related anyway, so what's the difference? If you mate with someone other than a family member, it's still the same, considering we all stem from the same two people. I personally have experienced what it's like to have incestuous thoughts, but it seems that all of society is strongly against it, with no good reason why. The only incest I have a problem with, is sister's and mothers and such, but I believe cousins are totally natural. Since society is against incest, especially close relations, I have to argue that marriage to a cousin is completely natural, and if not marriage, at least some sort of an attraction. Look at history; Franklin Delenor Rosevelt married his cousin, although distant, cousin none the less, so what's the difference? Why has no one complained about that? So I bring up this again; we are all related. Nothing is different than from marrying someone else than from a family member.

In responce to the 4th one up, I totally agree. Same goes for the one above me. Yes, their is a chance of a defect in the offspring, but as stated earlier, it is not often. In fact, I believe it has the same chance as a "normal" couple. My incest beliefs stem from a reverse psychology, I don't know if it makes it right, but I believe it none the less. When I was little, I had a "cousin"; (not my real cousin) who was a year older and wanted to do some childish hugging and kissing. We got in big trouble, "That's your cousin!"..blah blah blah. So then I think my mind took a reverse, like "Fine, you want to yell at me so much, I WILL like it" And ever since, I've felt a naturall attraction to a few of my cousins, which I have no controll over, and that nobody knows about. So I think society definetely takes a negative approach to something that can be so natural, and I think most people at least once in their life, have experianced those thoughts, but decide to play along with society so they don't look bad.

I totally agree with the fact that you might develop an attraction to your cousin do to growing up in separate homes. I in fact just met my cousin for the first time a few years ago, and I was instantly attracted. It has nothing to do with being "yuck" or "redneck" or whatever term you want to use, it is in fact natural, especially if you never met. And why exactly is it bad in the first place? All through history there's been incest, Albert Einstein married his first cousin, Marry and Joseph; the mother and step father of Jesus, they too were first cousins, so why does religion condemn it? Think about it. If your reason is because it has defects on a child...it's only 3-7%...same as anyone else. And if Adam and Eve were the first people, what about their kids? They would have kids, and who would they mate with? Each other, that's how we all got here, so in a way we're all related anyway, so why all the fuss?

How hilarious that all the posters claiming that there is nothing unnatural or shameful about incest, and are drawing from their own past experiences, are posting ANONYMOUSLY. So much for making their case.

I think it is amusing both that the pro-incest commenters are all posting anonymously, AND that the level of spelling and grammar in their posts is substantially below the average here. What's the research like for lowered IQ in offspring of incestuous relationships? Maybe their pro-incest stance is something shared by their biological parents...

My thought (and most people may not like it)and that's ok with me but I don't see a problem with adult incest (male to female) please use precausions (male to male)they can't prduce a child so really no precausions unless you count HIV or AIDS then yes use precausions.Now as for adult & child incest I believe the same way.I don't believe in forcing a child but if the child want to have sex with an adult thats fine it is only human nature.I don't judge at all and none of us should, what is right for one is not right for all.It's ok not to agree with incest but it's also ok to agress with incest,it's your call.We are all here for each other.Let's not distroy that.

Darwinism_clearly he studied this subject because he marrued his first cousin.The facts of incest are many disorders both physical and mental...keep the abortion clinics open!I would rather be dead then be an incestial child.ss/www.godmyspace7@yahoo.com

I am a libertarian agnostic, and yes, I too, have no moral problem with incest. Why should I? There's hardly any truly worthy moral arguments against incest. The only even semiworthy one I can think of is 2 people of the opposite sex possibly getting the woman pregnant and having an inbred child that will possibly be physically and/or mentally deformed. He/she will thus, among other things, have a harder life. Once society finds out about who his parents are, they will likely ostracize him, or at least treat his parents like shit.

But other than that, what's there to be guilty over? I've been pro-icnest for about a year or so now, and I see no reason to turn back anytime soon. The incest taboo is mostly religious bullshit about "natural morality" or "natural law", which doesn't exist. All morality must be based in science and reason, NOT what some fictional deity says. There's little reason for society to ban or look down upon consensual incest.

Of course I am totally against abuse. Why wouldn't I be? Libertarianism is all about consent and individual liberty. We Westerners, esp. in America, really need to get over our uptight attitudes about sex. Victimless crime laws like "statutory rape" are just silly and do not prevent actual rape by an older man/woman at all. Polygamy is not ALWAYS Mormon cults who force their daughters to marry older men. There actually are many polygamous couples, I'm sure, here in America and worldwide that are much less abusive. Sexual "deviancy" is only deviant because it's not the norm, not because it's "wrong." Practically nothing is wrong if it's consensual.

I call for a new kind of ethics, consent-based morality. It's not perfect, but it's a lot more scientific and rational. It doesn't simply rely on tradition for tradition's sake or look to some religion for answers. It goes with what works and what's proven.

And besides, people are people, for christ sake. Who the hell cares if the person you have sex with or get involved with is a sibling, a parent or someone unrelated??? Why should that matter? As long as both parties consent and are of sound mind, I could fucking care less. People should be free to embrace these feelings and approach the ones they love, even if incestually, not be shunned when they do or be forced to be something they're not. It's just as bad as gays in places like the Middle East forced to either marry the opposite sex just so no one is on to them (among other reasons), or admit they're gay and risk severe repercussions.

Our DNA is all pretty much the same as we are the same species. The differences among various races, ethnicities, etc. are small in comparison to the overall gene pool. Sure, it may not be advisable for everyone to have incestual sex with a relative (esp. without protection), but at least acknowledge that people do have these feelings from time to time, and they should not be forced to hide them because they're "dirty."

I understand that a few of you felt guilty after getting involved with relatives, and that may be "evolutionary" to an extent. But you have to remember not to employ the naturalist fallacy- just because humans are genetically or physically oriented towards one action does cannot necessarily imply right or wrong.

I resent the notion by my atheist friend above that I'm a "nutjob" just because I don't have a problem with incest. Why should I? As I've outlined in the preceding paragraphs, it's not that big a deal! It's not the end of the world if a few people have incestual relations out of 6 billion. And homosexual incest is even more of a gray area since they can't reproduce.

An atheist that accepts incest for the stupidest reasons. I cannot believe you, sir. How about being a rationalist for once?? That is exactly why I'm pro-incest-rationality. I have rationalized it effectively and demolished pretty much all of my opponents' arguments. You just parrot the same bs talking points that religion told you or society said, it seems. For shame.

The other argument I hear commonly is that "incest can stunt emotional and/or mental growth." While that argument may be backed by studies and have merit, it still does NOT mean that incest is wrong. That argument is a matter of practicality, not morality. If both parties consent and know what they are getting into, it doesn't matter. It's much the same for smokers, junkies, fatasses, etc. If they decide to consume too much and kill themselves, who am I to judge and get in the way?

Of course, the situation is complicated if there's, say, a family, not just the 2 people by themselves. But that's a wholly different argument and context. It's not the usual context we think of, either, when we talk incest.

And isn't it true that India has some state or area or section of its people that actually do openly (or at least within the household) practice incest?? And quite commonly, I might add. I forget their name, though. That's just one of probably several examples of actual, embraced incest cross-culturally. It would seem to add to the notion that the incest taboo is more cultural and societal than genetic. I'm of the belief that it is cultural, and we are essentially indoctrinated to believe it's wrong at an early age and keep having this belief reinforced by society. We are given social sanctions if we step out of bounds on this issue. People oftentimes react very negatively and sometimes are terrified if one of their own is attracted to them or another family member.

The Westermarck effect seems true, but have there been any further studies to show that it actually IS genetic and not just a result of societal conditioning? How do we know for sure that the societal indoctrination hasn't permeated these kids so much that they have internalized the incest taboo to an almost genetic or instinctual level? THAT's what we need to determine.

And to be honest, I actually do look at incest text-based erotica quite often on Literotica.com. So this is not just a purely academic view. I also find the idea kind of a turn-on. Forbidden love is hot. Breaking those boundaries for the person you love and not giving up is quite attractive, and that just strengthens the bond between 2 people even further. Having your closest relatives by your side in love like that would seem to be one of the purest relationships I can think of.

And plus, if a brother and a sister grow up extremely close, why shouldn't it be logical that they would take the relationship to the next level, or should, anyway? If they have those feelings for each other in their teenage years and into adulthood, I say, have at it. Of course, if the family suffers from a history of certain diseases or illnesses, esp. things like Down's syndrome, they should use protection and only have kids if they are absolutely assured by a scientist that their union could not have a good chance of producing defective kids. But other than that...

And I'm a bit of a pro-cougar kind of guy, too. I find just the idea of a cougar with a younger man very enticing. Sure, it may be an Oedipal Complex thing, but so what. Love is blind. And I kind of like the idea of "cradle-robber" (if the relationship is totally consensual), esp. if my "cradle" were being robbed in my teenage years (which it hasn't). Having to fight for the love of some older woman when society would be looking down on us at that age sounds interesting to me.

This also informs my views on the whole "teachers fucking students" scandals in recent years. On the professional side of things, yeah, maybe the teacher shouldn't be screwing her students because there's a major conflict of interest, for one thing. But on a moral level, I don't care. In fact, I'm kind of jealous, and I'm sure most guys are too.

Age doesn't matter. It's maturity levels and development that do. If you're some 20-year-old woman with a 15-year-old guy who can hold his own and has the maturity and/or mentality of a 20-year-old, it's pretty much OK. It's a fallacy to assume that age is the end-all be-all when it comes to relationships.

Of course, this does not mean I endorse pedophilia. I'm not a pedophile myself, and I'm no fan of little kids and adults, mainly cuz it's almost impossible for a kid to 'consent' at that age to sex and even know what's going on. Plus, they're too underdeveloped that any sexual activity would damage them in many ways. But if the kid is at least 13 or 14 and has crossed that threshold of puberty, then the rules change.

Treating teenagers like children as if they were still 8 or 9 is just ridiculous. They are not adults, yes, but they are not "children."

Hi there. Here's another sidelight on the issue. My novel Keaen, in order to be published had to have the breaking of the societal taboo against incest removed in order for the publisher to go ahead with publication. Never mind that ultimately it turned out that the perpetrators actually weren't siblings.

I had bitter arguments with the publisher of the first edition, before I finally yielded and basically took one of the most important elements out of the story. The things you do to get published! Of course, I ultimately self-published a second, unexpurgated edition; but that's another story.

The point here is that what I can only call a visceral reaction by the publisher and editors to the apparent breaking of a taboo, when it turned out that there actually wasn't any transgression after all, seems to support those who say that the taboo against incestuous activity—in this instance between consenting siblings, like those in the story at the beginning of this blog—is not biologically innate, but is imprinted on us by what amounts to social-moral brainwashing; most of which is, of course, religious; and which affects even those who may have rejected religion. The conditioning remains.

Needless to say I have no issue with Mark and Julie's actions. Indeed, I have always found the story oddly touching.

First off thankyou for grouping all the atheists up like another religion... /sarcasm

And a real thankyou to brando for the best response of all.

I feel the need to respond to a particular comment. That is, the one laughing at the Anon posters.The people who post about their incestuous experience are posting anonymously because they "find it almost impossible to discuss with one another". They cannot even talk about it with each other, let alone other people. The only reason you have the privilege to even know these stories exist is because the posts are anonymous...

Brief note on the story, and my response to the question: "Was it ok for them to make love?"

Incest taboo aside, are they hurting each other?No, they have a much better relationship as a result.

Are they hurting anyone else? Again, no. No other person is affected by this in any way.

Did anything good come of it?Yes, they have a better relationship now.

The only "wrong" thing that they have done is break an unjustified taboo. The "unjustified" part is the only weakness in my view that I can see, And despite my attempts I cannot elaborate upon this to a sufficiency which I find satisfying. So I leave you with brando's quote "That argument is a matter of practicality, not morality."

So what was the sum of this experience? One good thing and nothing bad. Is it morally right to condemn someone for something that has brought only good, and no harm?

My response is that in this situation they have done nothing wrong. So yes, I would say it is ok for them to have made love.

The argument that incest leads to defected off springs and hence morally or logically incorrect is a sham. Following the same argument, we should probably restrict people with hereditary diseases from reproducing. Save our precious gene pool from diabetes and high blood pressure. How many times have you asked people to provide you with there complete health profile before feeling attracted to them?

human morality has more to do with social conditioning than just some information passed through our genes. In a primarily theist, Christian evangelist society, sexual repression is a norm and the propaganda to create that morality against what it thinks as divergent sexual behaviors leads to such reactionary moral values.

Sexual attraction either incestuous or homosexual are as normal as a person preferring certain races. To say that white folks prefer white folks as potential mate due to genetic conditioning can also apply equally to centuries of white superamist racist conditioning.

The family structure so valued by the beloved lambs of god is full of hypocrisy. Sexual abuse especially of children is more common in the churches than households. Perhaps we should call a priest a 'gross sick sinful creature of god, or perhaps provide scientific discourse for their psychological illnesses' and ban the churches.

Human relationships are much more complex than these morons 9and those who wrote these religious texts)would like us to believe.

The god fearing perfect households produce children who pick guns and go on a murdering spree in schools and colleges. The degeneration of families is inherent in our social systems not in our sexual preferences. Those trying to explain the social culture would do well to read the history and development of current family structures which are themselves based on patriarchal oppression and as far away from perfect as possible.

All abusive sexual or non sexual relationships must be condemned.

Consensual relationships between adults on the other hand are fine regardless of whether you feel comfortable with it or not.

I am quite surprised that no one has noted that while many people have an aversion to incest there is clearly a large number of people are aroused by incest thoughts as evidence by the multitude of pornography and stories about incest available. I am wondering if in larger social settings the urge for incestuous relationships are neutralized by easily available mates out side the family. However, in small group settings where mates are limited, the sexual urge overcomes whatever kinds of aversions humans have to mate with other family members for males in particular.

As an example the stories of families sharing incest in isolated regions of the united states in the Kentucky mountains. This would be an example of where few available mates and being limited to isolated family groups cause some males to abandon their sexual morays and mate with family members. Limited number of available mates would explain even in large populations as well where an individual it might seem has a large number of available mates but in reality does not. Such as in a family that lives in the city but the mother is not sexually available; the father might over come his sexual morays to mate whit his children where he might not be able to convince a non familial adult female to mate with him for many reasons. A better example might a widowed grandfather in and extended family who sexual arousal could overcome his moral aversion to have sex with his grandchildren but not to his son or daughter because they are adults and have a developed sense of sexual morality. Understanding as well being an aged grandfather has no appropriate sexual mates available given his age and circumstances.

I think we all accept that sexual interaction among young siblings is very common. It is clearly a time when children often have limited availability of sexual mates other than their siblings.

For example a widowed grandfather in and extended family sexual arousal could overcome his moral aversion to have sex with his grandchildren but not to his son or daughter because they are adults and have a developed sense of sexual morality.

One could also look for support from the fact that priest who we would think would have a higher than average moral value have often engage in pedophilia. This is because conflict of celibacy and and refraining from natural sexual activity allows some priest to over come their moral aversion to their desire for sexual activity. Again children are targeted because of their undeveloped sense of sexual morays with possibility of no consequences.

Over coming the incest aversion may be natures way of the species to continue survive given certain conditions. If we took a hypothetical such as a father and daughter who were somehow shipwrecked on a deserted island with no chance of recovery. At some point I believe that it is more than likely the father and daughter would engage in sex. The fathers sexual urge would over come him or both of them and they would mate and continue the survival of the species. I think it is important to note that the male sex drive to mate is inordinately higher than females which allows men given circumstances circumstances to over come his moral aversion to having sex with inappropriate partners. Not that females don't have sexual urges but they do so at a much lower lower level. It seems to be the burden of males by their increased hormonally controlled intensity to mate to over come sexual morays.

It is not with out note as well evolutionarily females remain physically weaker than males so that at times of lack of social structure males can force females to mate and continue the survival of the species. In times of developed social structure females are in more control of choice of sexual partners choosing mates that are likely to protect and provide for offspring. The female urge in essence isn't as much to mate as it is to have a mate to produce and protect off spring with.

In response to Anonymous above, I am reminded of the story of Noah in the Judeo-Christian bible - Noah's daughters were told by their brothers to have sex with their father while he was asleep to propagate the species. The brothers would not procreate with their sisters.

I will disagree with atheists. Revulsion to incest is certainly a biological adaptation. I was never religious, my parents are atheists and so am I and quite honestly I was never attracted sexually to sisters or my mother. Just a mere thought of it evokes strong disgust in me.

I'm not sure if anyone will see this comment, considering how old this post is, but I'm surprised that nobody mentioned the fact a person's revulsion or not to incest has much to do with how attractive the relative is.

I have an on again, of again incestuous relationship going between my model / actress first cousin, and I have no problem with it. We don't have sex in person, but we do have fun with each other over the net with webcams and such. She's objectively hot.

I would certainly consider a sexual relationship with my younger sister, too. She is even hotter than my cousin! Looked at objectively, she is a 9.

Men are genetically programmed to find women attractive who share certain traits - like a certain body shape, weight, personality, skin tone and smoothness, etc. The same holds true for women in regards to their attraction to men.

If your sibling is a 3 out of 10, it would be easy to find revulsion in incest. If he / she is a 9 or a 10, it becomes much harder.